Automatic telephone substation circuits



. Aug. 25, 1925.

W. T. POWELL AUTOMATI TELEPHONE UBSTA'I'IQN CRQUFIS Filed Nov. 15. 1922 n 2 Shntlfsxgt `l PM la l lHC., `\5 /H J y f r l 3a l -as a1 FlGZ HCA INVENTOR wmv-RED T. POWELL BYQ. l j' l ATTORNEY Aug. 25, i925.

A 1,551,171 w. T. POWELL AUTOMATIC TELEPHONE SUBSTATION CIRCUITS WNFRED T. POWELL ATTORN EY Patented Athug. Z5, i925.

untreu sr'rss Peteur Orrin-a1.,

vniirnnn r. POWELL, on nooiinsmnn, New YORK, assIeuOn Canteen rnnnrrionn Manurnorrrnm oOnronarION on NEW YonK.

G COMPANY, F ROCHESTER, NEW YORK, A

AUTOMATIC TELEPHONE SUBSTATION CIRCUITS.

Application l'edNovember 15, 1922. Serial No. 601,143.

To @ZZ whom t may concern.' I

lle it knownV that l, finivano T. POWELL, a citizen of the Unit-ed States, residing at Rochester, in the county OI" li/lonroe and State of New York, have invented certain new and useful Improvements `in Automatic Telephone Substation Circuits, oi' which the 'following is a full, clear, concise, and exact description. y

This invention relates to substation circuits of the type employed in automatic telephone systems; 1

ln the telephone substation circuits eniployed in automatic telephone. systems it is imperative that the impulses generated by the impulse transmitter be pertectly transmitted without interference from the microphone transmitter; also in said substation circuits it is necessary to prevent the noises 20 from the impulse transmitterbeingheard? in the t-elephone receiver. The present invention is oit special use in substation circuits where the woll known desk stand and bell box are employed,l in such air ot conductors extending between the bell' box and the desk stand be small.

The present invention, therefore, has for its purpose 'substation circuits in which the microphone transmitter is disabled during the operation of the impulse transmitter and in which thetelephone receiver is likewise disabled during the transmission ot impulses while the number of conductors be tween the bell boi: and the desk stand are reduced to thefminimum.

In the drawings, Figures' l, 2, 3, t, 5, 6, 7, and 8 represent modified circuit arrangements tO accomplish the aboveout'lined results. ln each of these ligures the portion thereof at the lett of the dotted line reprev`` sents the desk stand while the portion of each ligure at the rightI of the dotted line represents equipment within the bell box. 15 The impulse transmitter referred to in this disclosure may be similar to that dis-v closed on pages 34s and 35 oi' Automatic Telephony by Smith and Campbellflirst edition, when the shunt springs are re-ar- 50 ranged ina manner to be pointed out.

lt is believed that the invention will best be understood by describing the' arrange# ment ot the conductors in the various modiv fic-ations of the present invent-ion. Reterarrangement it is essential that the number ring,lirst of all, to Fig. 1, conductors 10 and 11 are the conductors "of the well known telephone line which connect the substation to the main exchange. Conductor `10 is nor# mally bridged to conductor 11 through the condenser 12 and the substation signal' or ringer 13. This bridge iszcontrolled through the contacts le ot the well known type o'l hook-switch which maintains contacts 11i closed when the receiver l5 is suspended from. the switch-hook. A second bridge across the line conductors 10 and 11 is normally open at contacts 16 until the receiver is removed from the switchhook. This second bridge is taceable from line conductor 10, primarywinding 17 of the induction coil, through the microphone transmitter 18, impulse springs 19, normally open-ed contacts 16 of the hook switch, to the line conductor 11. A third bridge including the receiver 15, a second condenser and the secondary winding oi the induction 4coil 21' is connected at one'end to the second bridge at a point between the microphone transmitter 18 and the impulse springs 19 of the mentioned impulse transmitter while the other end of this third bridge is connected to the second bridgewat a point between the? primary wind` ing 17 of the induction coil and the microphone transmitter 18. It will be seenl that, in addition to the impulse springs 19, the impulse transmitter is also provided `with shunt springs designated 22, 23 and 24. These springs,.it will be noted, are normally open except when the impulse springs 19 are being opened and closed under the act-ion ot the impulse transmitter at which time they are closed.

The operation of this substation arrangement is substantially as follows: The subscriber when he desires to initiate a call, removes his receiver 15 from the hook-switch,

at which time the hook-switch s urines V1(5 are Closed so that the second mentioned bridge including the microphone transmitter andthe impulse transinitter are connected across the line conductors 10 and 11. The subscriber then` operates his impulse transto come into engagement. The impulse mitter, permitting the springs 22,' 23 and 24 transmitter `on its retrograde imoven'ient ifn-` termittently opens and closes the impulse s irinos 1-9until the.'` im iulse'transmitter has completed its operation, at which time shunt springs 22, 23 and 24 are opened and the impulse springs 19 remain closed. It will thus be seen that during the period that the impulsesprings 19 are intermittently operated, a shunt 'circuit is closed about Ythe microphone transmitter 18 so that the impulses are transmitted to the main exchange, through conductor 10, p-rimary winding 17 of the induction coil, impulse springs 22, 23 and 24 through the impulse springs 19, hook-switch contacts 16 and line conductor 11 to the main exchange. At this time also the receiver is included in a closed circuit including conductor 25, shunt springs 23 and 24, and conductor 26. Themicrophone transmitter 18 is also short-circuited at this time by conductor 26 and shunt springs 22 and 23. When the substation of Fig. 1 is called, alternating signaling current is transmitted from the main exchange through line conductor 10, the condenser 12 and ringer 13 in series, normally closed hook-switch contacts 14, through the lower line conductor 11 to the main exchange. The subscriber at the substation on hearing the signal removes the receiver from the switch hook, at which time the second mentioned bridge circuit is closed across the conductors 10 and 11 and the first bridge is opened. The second mentioned bridge is, or course, a portion of the conversational circuit.

In the arrangement shown in Fig. 2 the line conductors 27 and 28 represent the well known telephone line terminating at their ends in the main exchange and in the terminals of the welhhnown form of bell box. As here shown, the ringer 29 is normally bridged ,across these conductors in a circuit including the condenser 30, the conductors 149 and 150 and contacts 9. Asecondbridge across these conductors includes the'primary winding 32 of the induction coil, hookswiteh contacts 33, impulse springs 34, microphone transmitter 35, the receiver 31, through the line conductor 28. A third bridge including the secondary winding 36 of the induction coil terminates at one end in the conductor 'between the ringer 29 and the condenser and at its other end in the normally opened contacts 37 of the hookswitch, which connects this last mentioned bridge to the second bridge at a point between the primary induction coil 32 and the impulse springs 34. In this arrangement also the shunt springs consist of three non mally opened springs and, as in the case ofk the rst described arrangement, these springs short circuit the microphone transmitter and the telephone receiver 31.

In the modification disclosed in Fig. 3, the line conducto-rs41 and 42 are normally bridged by a circuit including theringer 43, the condenser 44, conductors 45 and 46, nori mally closed hook-switch contacts 47 and 48, conductor 55, impulse springs 49 to line conductor 42. A second bridge across these conductors which is closed only when the receiver 50 is removed from the switch-hook is traceable from the lconductor 41, primary winding 51 of the induction coil, normally opened contacts 52 of the hook-switch, microphone transmitter 54, receiver 50, conductor 55, impulse springs 49 to the line conductor 42. A third bridge including the secondary winding 56 of the induction coil is Vconnected to the first mentioned bridge at a point between the ringer 43 andthe condenser 44. The other end of this bridge is connected by the hook-switch contacts 53 to said second bridge at a. point between the primary winding 51 of the induction coil and the microphone transmitter. In this instance also the shunt springs 57, 58 and 59 short circuit the microphone transmitter 54 and the receiver 50.

In the arrangement shown in Fig. 4 the conductors 61 and 62 represent the two sides of' the telephone line. These conductors are permanently bridged by a. conductor including the biased ringer 63 and the condenser 64. It sho-nld be mentioned that this ringer is biased in order to prevent the so-called tapping of the bell when the impulse springs 65 of the impulse transmitter are operated. A' second bridge across the conductors 61 and 62 is completed when the subscriber removes his receiver from its switch hook and is traceable from conductor 61, primary winding 66 of the induction coil., hook-switch contacts 67, through the re ceiver 68, microphone transmitter 69, the impulse springs 65, hook-switch cont-acts 70 to the line conductor 62. A third bridge including the secondary winding 71 of the induction 'coil is connected to the first bridge at a. point between the ringer 63 and t-he condenser 64. rIhe other end of this bridge is connected to said second bridge at a point between the microphone transmitter 69 and the receiver 68. The shunt springs include normally opened springs 72, 73 and 74. These shunt springs, as previously described, are closed during the period that the impulse springs 65 are intermittently operated and serve toshort circuit the receiver and microphone transmitter.

In Fig. 5 a. slightly different arrangement of the substation circuit is disclosed. The line conductors 77 yand 78 are normally bridged by a 'conductor including the condenser 79, ringer 80 and the normally closed hook-switch contacts 81.Y A seco-nd bridged circuit is connected to the mentioned line conductors and ext-ends from conductor 77, primary winding 82 of the induction coil, microphone transmit er 83 and the tele-phone receiver 84 in series, normally closed shunt springs 85 of the impulse transmitter, normally open ycontacts 86 ot the hook-switch to the conductor 7S. A third bridge including the secondary winding 87 ofi the induction coil and a second condenser 88 is connected at one end to said second bridge at a point between the primary winding 82 of the induction coil and the microphone transmitter 83. rlhe other end of this third bridge is connected to said second bridge at a point between the microphone transmitter 83 andthe receiver 811. lin this instance, during the transmission of impulses, the springs 85 are open and the springs 89 are closed, from which it will be seen that the microphone transmitter and the telephone receiver are on open circuit during the time that the impulses are being transmitted through the mentioned line conductors. The impulse circuit is traceable from conduc-tor 77, primary winding 82 of the induction coil, impulse springs 90, shunt springs 89, contacts 86 to the line conducto-r 78.

1n the arrangement diagrammartic-ally shown in Fig. 6 the line conductors 91 and 92 are normally bridged by a conductor including the condenser `93, the ringer 941 and the normally closed hoch-switch contacts 95. A second bridge is connected across the line conductors from conductor 91, primary winding 96 of the induction coil, microphone transmitter 97 and the receiver 98 in series, normally closed contacts 99 ot the shunt springs, impulse springs 100, normally open hoolswitch contacts 101 to the conductor 92. A third bridge including the secondary winding 102 of the induction coil and the condenser 103 is connected to said sec-ond bridge at a point between the primary winding of the induction coil 96 and the micro-phone transmitter 97. The other end of said bridge is connected to said second bridge at a point between the microphone transmitter 97 and the receiver 98. During the transmission oi impulses the shunt springs 99 are open and the springs 1041 are closed so that the circuit Yfor transmitting impulses to the main exchange now extends from line conductor 91, primary winding 96 of the induction coil, contacts 10-1, impulse springs 100, hookswitch springs 101 and line conductor 92 to the main eX- change.

In the modified form shown in Fig. 7 the line conductors 105 and 106 are permanently bridged by the conductor including a con` denser 107 and a biased ringer 108. A second bridge across these conductors is traceable from conductor 105, primary winding 109 of the induction coil, impulse springs 110, hook-switch contacts 111, microphone transmitter 112, receiver 113, normally closed shunt springs 114, hook-switch contacts 115 and line conductor 106. A third bridge including the secondary winding' 116 of the induction coil is connected' to said bridge at a point between the condenser 107 and'ringer 108, and at its other end is connected to said second bridge at a point between the microphone transmiter 112 and the receiver 113. lt will be noted in this instance that the shunt springs 1111- are opened during the operation o the impulse transmitter so that the microphone transmitter and receiver are placed on open circuit at this time. The circuit over which the impulses are transmitted to the main exchange entends from conductor 105, primary winding 109 of the induction coil, impulse springs 110 normally opened shunt springs 117, hoolfsvvitch contacts to conductor 106.

ln the disclosure ot Fig. 8 the line conductors are shown at 118 and 119. These conductors are permanently bridged by a circuit including the biased ringer 120 and the condenser 121. A second bridge extends from conductor 118, through primary winding 122 of the induction coil, microphone transmitter 123, impulse springs 124-, normally opened hook-switch contacts 125fto line conductor 119.v A third bridge including the permanent magnet receiver 126, the normally opened hook-switch cont-acts 127 and the secondary winding 128 of the induction coil .is connected at one end to said i'irst bringe at a. pointbetween the ringer* 120 and the condenser 121. The otherend of said third bridge is connected to said second bridge at a point between the primary winding 122 of the induction coil and the microphone transmitter 123. Here also the shunt springs generally designated 129, close shunt circuits about microphone transmitter 123 and the receiver 126 so that the impulse circuit extends from conductor 118, primary winding 122 of the induction coil, shunt spring contacts 129, impulse springs 1211, hook-switch contacts 125 and line conductor 119.

What is claimed is 1. In a substation circuit arrangement, two line conductors, a bridge across said conductors including the primary winding ot an induction coil, a microphone and. a telephone receiver, ay normally closed bridge across said conductors including' a signal and a condenser, a third bridge including a secondary winding ot said induction coil, said .third bridge being connected to said rst bridge at a point between said Signal and said condenser, the other end of said third bridge being connected to said second bridge at a point between said microphone and said primary winding of said induction coil, a hoolrswitch serving to close said iirs't and third bridges, an impulse sender having a pair ot impulse springs and a plurality ot shunt springs arranged vto be closed when said impulse springs are operated to render said microphone and telephone re-` ceiver inoperative, and an impulse path extending across said line conductors includA tending through said pair of' impulse springs.

2. In a substation circuit arrangement, two line conductors, a bridge across said conductors including the primary winding of an induction coil, a microphone and a telephone receiver, a normally closed bridge across said conductors includinga signal and a condenser, a third bridge including a secondary winding of said induction coil, said third bridge being connected to said first bridge at a point between said signal and said condenser, theV other end of ysaid third bridge being connected to said second` bridge at a peint between said microphone and said primary winding of said induction coil, a hoolrswitch serving toclose said first and third bridges, an impulse sender hav ing a pair of impulse springs and three normally open shunt springs arranged to be closed when said impulse springs are being actuated, said shunt springs when closed functioning to render said microphone and telephone receiver inoperative, and an im pulse path across said line conductors including a portion of said lirst bridge and extending through said impulse springs and through the shunt springs.

ing a portion of said first bridge and exn` 3. In a substation circuit arrangement, an induction coil, a signal and a condenser forming one unit, a microphone, a telephone receiver, an impulse sender, and a switchhool; forming a second unit, two line conductors, a bridge across said conductors including the primary winding of said induction coil, said microphone and said telephone receiver, a normally closed bridge across said conductors including said signal and said condenser, a third bridge including the secondary winding of an induction coil connected across said first and second bridges, said hoolswitch functioning to close said irst and third bridges, an impulse sender having a pair of impulse springs and a plurality of shunt springs arranged to be closed when said impulse sender is operated, said shunt springs when closed serving to render said microphone and said tele-phone receiver inoperative, an impulse circuit including a portion of said first bridge and extending through said impulse springs, the connections for said bridges between said first and second units including not more than four conductors.

In Witness whereof, I hereunto subscribe my name this 14th day of November A. D. 1922.

WINFRED T. POWELL. l 

